Extend the existing incremental benchmark with an opt-in --matrix mode for affected-frontier scenarios. The matrix isolates repos and caches per case, records publish_kind and exact/fallback reasons, compares incremental output to a fresh FAST rebuild with canonical SQLite graph rows, and cleans up generated work roots by default.
This is a measurement and regression harness, not a default-policy change. incremental_reindex remains default-off until the broader matrix, freshness semantics, cleanup, and speedup gates are satisfied.
Validated with python3 -m py_compile scripts/benchmark-incremental-speed.py, git diff --check, bash scripts/check-source-safety.sh, and an escalated two-case matrix smoke for go_modify_1/go_modify_2.
Signed-off-by: Andrew Hundt <ATHundt@gmail.com>
Andrew Hundt
a35f58fcb0